topic Re: Query on Quorum Disk & Fenceing in Operating System - Linux

Query on Quorum Disk & Fenceing

Md. Minhaz Khan — Mon, 18 Oct 2010 07:03:00 GMT

Dear Experts,

In my company, our Application Vendor configured "Two node Redhat cluster" with database fail-over. During "UAT" we have
find that they didn't configure Quorum disk for this cluster plus they use "Manual Fencing" which is not recommended by Redhat
for production environment. Though our each server (Server Model: HP DL380 G5) has HP ILO port but they didnâ t used it as fencing
device. Now i have below query about their configuration:

1) If we didnâ t configure Quorum disk then what would be a split-brain condition if Heart-beat Network connection (192.168.101.1 & 192.168.101.2) lost ??

**Note: In our environment, connection between (192.168.101.1 & 192.168.101.2) are made using cross cable.

172.16.10.101= Sever1 public LAN IP
172.16.10.102= Sever2 public LAN IP
172.16.10.104= Cluster Service IP

2) If we didnâ t have Hardware fencing like HP ILO then what type of problems may arise??

I request you please recommend us whether or not Quorum Disk & Hardware Fencing is required in our "Two node Redhat Cluster" environment. If yes then please give us some explanation so that we can assist our Application vendor to configure Quorum Disk & Hardware fencing.

I have attached necessary files for our cluster configuration with this mail. If you need more information, please let me know

Thanks
Minhaz

Re: Query on Quorum Disk & Fenceing

FLQ — Mon, 18 Oct 2010 08:52:11 GMT

Hi Minhaz,

You really should have both Quorum disk and Auto fencing.

First, if you lose your heartbeat connection, the two nodes will think that they should own the cluster and try to form it by themselves which could lead to both nodes trying to mount the same filesystem resulting in filesystem corruption.

Second, auto fencing is preferable because it could take quite a bit of time for a human to be aware of a problem situation and react to it (fence the problem node). In auto mode, the problem node would be rebooted almost instantly by ILO.

This is what we are using for quorum disk and fencing configuration.

You can also setup some extensive logging of your cluster like this:

and configure /etc/syslog.conf to send "local4.debug" in /var/log/cluster.log

Hope that helps.

Re: Query on Quorum Disk & Fenceing

Md. Minhaz Khan — Mon, 18 Oct 2010 09:26:15 GMT

Dear Experts,
One more query, as our server model is "HP DL380 G5" so we want to configure ILO port of this server as fence device. Can we able to configure this ILO port as fence device. If yes do we need extra license for ILO port ??

Thanks
Minhaz

Re: Query on Quorum Disk & Fenceing

Md. Minhaz Khan — Mon, 18 Oct 2010 09:28:18 GMT

>> If yes do we need extra license for ILO port ??

Is HP ILO needs any license like HP MP.

Re: Query on Quorum Disk & Fenceing

FLQ — Mon, 18 Oct 2010 09:32:58 GMT

Hi Minhaz,

as far as I know, ILO2 does not need extra licensing to use it as a fence device.

The fence daemon will issue a reboot command in the same way as you would do it in the ILO interface.

Re: Query on Quorum Disk & Fenceing

Md. Minhaz Khan — Mon, 18 Oct 2010 11:38:39 GMT

Dear Experts,

Any more justification ? otherwise i am going to close the thread.

Thanks
Minhaz

Re: Query on Quorum Disk & Fenceing

Md. Minhaz Khan — Tue, 19 Oct 2010 09:42:00 GMT

Thanks a lot everybody.